This invention relates to lid structures, and, more particularly, to a flexible lid for sealing metal, fiber or plastic drums.
Drums, pails or other containers formed of steel, aluminum, plastic or wound liner board are commonly used to transport a variety of materials including certain pharmaceutical products which must be tightly sealed to avoid damage or contamination. Many commercially available drums are formed with an open top having a curved or contoured lip. One lid structure which is commonly used to seal the top of such drums includes a circular sheet of metal or plastic having a downwardly extending flange. The lid is placed over the open top of the drum so that its flange extends over the lip and around the outer wall of the drum. A metal locking ring is then fitted about the flange and tightened to seal the flange to the lip and to the drum wall.
A problem with this type of closure is that the circumference of open tops of drums, and the diameter of their contoured lips, may have some degree of dimensional variance due to production tolerances or as a result of distortion after repeated use. The combination of a rigid top and locking ring may not produce a tight seal of drums whose circumference or lip diameter vary in dimension from a predetermined range to any significant degree. In addition, the locking ring is relatively expensive and adds substantially to the total cost of the drum.